Pallets of the type shown in Fielder U.S. Pat. No. 5,042,397 have increased in popularity, as the consequences of the use of conventional forklift pallets have become evident, especially those related to those which use wood in their construction. The use of wood inherently involves the cutting down of trees.
It is a fact that in the United States, the amount of wood consumed annually for making forklift pallets is second only to the amount of wood used in the paper industry. As another example, in Costa Rica, an astonishing 28% of the wood presently being cut down from its virgin forests is used for pallets. Many of these pallets will be used only for a one way trip, because it is too costly to ship them back.
These consequences are long term. To some extent they can be alleviated by advanced foresting practices, but the destruction of a virgin forest, together with its ecological systems, is a serious price to pay for the shipping of products. There are other concerns of greater immediacy, especially in direct cost where shipments are measured by weight, and in public health.
Pallets are exposed to all kinds of environments and pollutants. They are often placed on the ground near animals and other sources of pollution. They are porous, and can be saturated with water. This water will bring weight with it, which when weight is an economical determinant, will limit the amount of product that can be transported in a weight limited shipment, or which can increase the shipping costs when the shipment is costed out as a function of weight. This is perhaps the best understood consequence of the use of porous materials for pallets.
However, also the water constitutes a suitable medium to support living organisms. Outbreaks of diseases such as cholerea have been traced to forklift pallets. These pallets often rest atop stored loads, and the pollutants are frequently transferred from the pallets to their loads, and then to whomever handles the products. Because wooden pallets can not effectively be sterilized, they represent a serious risk, whose extent has only recently begun to be appreciated.
The pallet shown in the Fiedler patent is lightweight, non-absorbtive, readily cleaned and sterilized. It is strong enough for applications comparable to those for which wood pallets are use, with nearly identical dimensions.
The instant invention is one improvement over the Fiedler patent. The Fielder patent is incorporated herein in its entirety by reference for its showing of such a pallet, of suitable materials of construction, and of methods for making it.
In the course of preparing to manufacture Fielder-type pallets on a high-rate production basis, problems and opportunities for improvement in the process and in the product have become apparent. It is an object of this invention to disclose and to claim these.
This product is substantially entirely made of organic plastic material. It includes a reinforcement element and a cover which are flexible prior to incorporation in the pallet, and a foam which hardens the assembly. It is best practice to make all elements from the lengths of the same composite construction, cut to length and bonded together.
In the course of manufacture, there are significant lengths of time when nothing is rigid except the mold which contains the materials that are to form the basic structural material. As a consequence, there is considerable difficulty inherent in holding the elements of the slats in place while the foam is injected and cured, in a continuous process. One could readily jig up the flexible components and make the slats one by one. It such an event, the pallet would cost too much even to be considered, no matter what are its advantages.
This invention provides a slat construction which includes a skin, an internal corrugation, and a buttressing foam that fills in the spaces between the corrugation and the skin. This slat is amenable to manufacture to sufficiently close dimensions in a continuous flow production system.